| DaveP 
Tks to David Carlisle for the advice.
DTD - doc.dtd
<!ELEMENT doc (section)+>
<!ELEMENT section (p)+>
<!ELEMENT p (#PCDATA)>
Root file - doc.xml
<!DOCTYPE doc  SYSTEM "/sgml/mine/doc.dtd"[
<!ENTITY sect1 SYSTEM "sect1c.xml">
<!ENTITY sect2 SYSTEM "sect2c.xml">
<!ENTITY sect3 SYSTEM "sect3c.xml">
<!ENTITY dtd "IGNORE">
]>
<doc>
      <!-- Calls in the section *contents*, sans doctype -->
§1; 
§2;
§3;
</doc>
section file - sect (n).xml
<!DOCTYPE doc SYSTEM "doc.dtd"[
<!ENTITY sect1c SYSTEM "sect1c.xml">
]>
    <!-- Similarly, calls in the *contents*, sans doctype -->
§1c;     
<!-- Above is duplicated for  n other files -->
Section 1 contents file sect1c.xml
 <section>
   <p>Para in section 1</p>
 </section>
Stylesheet
<?xml version="1.0"?>
<!DOCTYPE xsl:stylesheet [
<!ENTITY nbsp " "> 
<!ENTITY sp  "<xsl:text> </xsl:text>">
]>
  
<xsl:stylesheet
      xmlns:xsl="http://www.w3.org/1999/XSL/Tranform"     version="1.0"
      xmlns:xt="http://www.jclark.com/xt"
    extension-element-prefixes="xt"
      version="1.0">
<xsl:output type="html"/>     <!-- Main file -->
<xsl:template match="/">    <!-- Only template -->
  <html>      <!-- Main file output -->
<head>
   </head>
<body>
                  <!-- Generated Text -->
<p>This is from the stylesheet  </p>     
  <xsl:for-each select= "file://p">
         <!-- Access all files from the root file -->
<p> <xsl:value-of select="."/> (Accessed from  root) </p>
</xsl:for-each>
</body>
</html>
 
    
        <!-- Now generate one file per section -->
  <xsl:for-each  select="/doc/section">
         <!--Generate a number from section posn
<xsl:variable name="docnumber">  
- -->
    <xsl:number value="position()"
format="1"/>
   </xsl:variable>
              <!-- Append the number to the filename -->
   <xt:document method="html" href="sect{$docnumber}.html">
<html>
<head>
</head>
<body>
               <!-- Output into the section files -->
    <p><xsl:value-of select="p"/> </p>
</body>
</html>
   </xt:document>    <!-- End of sectional output -->
  </xsl:for-each>    <!-- End of each section -->
 </xsl:template>     <!-- End of template -->
</xsl:stylesheet>    <!--End of stylesheet -->
Output (main file)
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
</head>
<body>
<p>This is from the stylesheet  </p>
<p>Para in section 1 (Accessed from  root) </p>
<p>Para in section 2 (Accessed from  root) </p>
<p>Para in section 3 (Accessed from  root) </p>
</body>
</html>
Output (sect1.html)
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
</head>
<body>
<p>Para in section 1</p>
</body>
</html>
Ditto for other output files, sect (n).html
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